Purification system for dry cleaning separator waste water

Abstract

A method and apparatus for purifying separator waste water from a dry cleaning process. The present invention utilizes 3 stages of purification. In Stage one, highly contaminated separator waste water is put into a solvent separator tank. Liquid solvent settles out of the separator waste water, sink to the bottom of the solvent separation tank where it accumulates below the separated water. In Stage 2 air bubbles are introduced through the separated water, stripping out much of the solvent which is dissolved in the separated water and reducing the dissolved solvent concentration. This air stripping process dramatically extends to useful life of the granulated carbon in the granulated eaton filter. Stage 3 takes the air stripped water and filters it through a granulated carbon filter, which results in the carbon purified water having a dissolved solvent of less than 0.7 parts per million. The carbon purified water can then be safely and economically disposed of without harming the environment.

What is claimed is: 
     
       1. An apparatus for purifying separator waste water from a dry cleaning process comprising: a separator tank with sides, a top end and a bottom end, an inlet located near the top end of the separator tank for the introduction of dry cleaning waste water, the dry cleaning waste water containing solvent and water, the solvent settling by gravity below the separated water;   a solvent exclusion weir located in the separator tank, the solvent exclusion weir containing an inlet that allows separated water to enter the exclusion weir located near the top of the separator tank;   a first pump for moving the separated water from the solvent exclusion weir to an air stripping tower;   the air stripping tower having sides, a top end and a bottom end, the separated water entering near the top of the air stripping tower, a bubble ring located near the bottom of the air stripping tower allowing air bubbles to be in contact with the separated water, the air bubbles dissolving solvent in the separated water forming air stripped water;   a second pump for moving the air stripped water from the bottom end of the air stripping tower to the top of a carbon filter;   the carbon filter having sides and a top and a bottom, the air stripped water entering the top of the carbon filter, the dissolved solvent in the air stripped water being filtered by the carbon filter forming carbon purified water exiting from the bottom of the carbon filter; and   a third pump for moving the carbon purified water from the bottom of the carbon filter to an evaporation nozzle for evaporating the carbon purified water into the air.   
     
     
       2. The apparatus of claim 1 further comprising a level device including a solvent level float located inside of the separator tank, the solvent level float moving up and down inside the separator tank and regulating the power to the first pump for moving the separated water from the solvent exclusion weir to the air stripping tower the first safety device stopping the power to the first pump when the solvent level in the separator tank reaches a pre-set level. 
     
     
       3. The apparatus of claim 1 further comprising an overflow device including an overflow tube with a top end and a bottom end, the overflow tube connecting the air stripping tower to the separator tank, the top end portion of the overflow tube being located inside the air stripping tower and the bottom end portion located inside the separator tank, a drain port being located near the top of the overflow tube inside the air stripping tower, a solvent dissolvable styrene fuse covering the drain port such that when the styrene fuse is dissolved by solvent, the air stripped water flows into the drain port of the overflow tube and exits the overflow tube in the separator tank. 
     
     
       4. The apparatus of claim 1 further comprising a carbon recirculation pump, the carbon recirculating pump moving the carbon purified water exiting from the bottom of the carbon filter to the top of the carbon filter to be filtered again. 
     
     
       5. An apparatus for purifying separator waste water from a dry cleaning process comprising: a separator tank for separating waste water into separated water and solvent, the solvent settling by gravity below the separated water, the separator tank having an inlet located near a top end for the input waste water and an outlet located near a bottom end for removing the solvent settled by gravity;   an air stripping tower having an inlet near a top end of the air stripping tower for the separated water, a bubble ring located near a bottom end of the air stripping tower allowing air bubbles to be in contact with the separated water, the air bubbles dissolving solvent in the separated water forming air stripped water, an outlet for removing the air stripped water from the air stripping tower;   a first pump connected to the separator tank and the air stripping tower;   a first device controlling the first pump, the first device stopping the first pump in response to the solvent in the separator tank reaching a pre-set level;   a carbon circulation tower having an internal carbon filter, the carbon circulation tower having an inlet near a top end for the air stripped to enter, the dissolved solvent in the air stripped water being filtered by the carbon filter forming carbon purified water, an outlet for removing the carbon purified water from the carbon circulation tower;   a second pump connected to the air stripping tower and carbon circulation tower;   an evaporation nozzle for evaporating the carbon purified water; and   a third pump connected to the carbon recirculation tower and the evaporation nozzle.   
     
     
       6. The apparatus of claim 5 further comprising a carbon recirculation pump for moving the carbon purified water exiting the carbon filter back into the carbon filter to further filter the carbon purified water prior to its removal from the carbon circulation tower. 
     
     
       7. The apparatus of claim 5 further comprising: a second device including an overflow tube with a drain port connecting the solvent separator tank and the air stripping tower; and   a solvent dissolvable fuse located in the air stripping tower covering the drain whereby if liquid solvent is introduced into the air stripping tower, the fuse is dissolved by the solvent and the fluid in the air stripping tower is removed through the overflow tube.